Alkoxyl lignin halide resins and process



Patented Nov. 1, 1949 ALKOXYL LIGNIN HALIDE BESINS AND PROCESS RaphaelKatzen, Eugene, 0reg., assignor, by

mesne assignments, to Diamond Alkali Company, Cleveland, Ohio, acorporation of Dela- No Drawing. Application November 15, 1945.

' Serial No. 628.974

301aiml. (01. 260-124) This invention relates generally to the art ofpreparing resinous substances, and more particularly to a method ofpreparing light-colored, transparent, alkoxyl halide resins and to theresulting compositions.

In the plastics industry light-colored, transparent or translucentresins are generally widely useful and of greater value thandark-colored, opaque resins, which do not lend themselves readily topigmentation and are unsuited for efficient light transmission. Onlydark-colored and opaque lignin resins have been known to the prior artheretofore and there has been, therefore, an unsatisfied demand in theindustry for lightcolored, transparent or translucent lignin resinswhich would open new fields to inexpensive, heatstable lignin resins.

There are two important reasons for the failure of prior efforts toproducesuch a resin. In the first place, a suitable intermediate rawmaterial has never been prepared, so far as I know, the lignin of theprior art being dark-colored to begin with, and invariably becoming evendarker upon resinification Secondly, no process was known by which alight-colored, transparent or translucent lignin or lignin derivative,if available, could be converted into a resin having the samecharacteristics.

Light-colored, transparent, low-polymer alkoxyl lignin halides have nowbeen described in copending application Serial Number 647,214, filedFebruary 12, 1946. These substances, un-

like other lignin derivatives known to the art,

have the light-color and transparency which is desired in the finalproduct and are, therefore, the only lignin derivatives of likelysuitability as intermediate raw materials in the preparations of thedesired resins.

Alkoxyl lignin halides of this description can be prepared according tothe processes described in the aforementioned copending application. Asa specific example thereof, methoxyl lignin chloride is prepared bytreating a mixture containing lignocellulosic material, methanol, andless than about of water, with chlorine while said mixture is maintainedin the temperature range between about 45 C. and about the boiling pointof methanol and at a pressure ranging from atmospheric to about 200pounds per square inch. After about to about 3 hours of this treatment,depending upon the temperature at which the reaction is efiected, themethanol is separated from the solid portion of the mixture andintroduced into several times its own volume of lignin chloridedissolved in the methanol precipi- Lates and can readily be separatedfrom the resulting alcohol-water solution.

The term alkoxyl is use herein in its usual generic sense and is to beinterpreted as meaning methoxyl, ethoxyLpropoxyl, iso-propoxyl, butoxylor the like. Since natural lignin is known to contain methoxyl groups invarying proportions, depending upon the wood species in which it occurs,but is not known to the art as alkoxyl lignin," I have used the termalkoxyl to indicate modification of natural lignin by addition to thelignin molecule of alkoxyl groups. Thus wherever alkoxyl lignin halide"is referred to herein a lignin halide is described which contains, inaddition to naturally occurring methoxyl groups of the lignin, methoxyl,ethoxyl and/or other alkoxy] groups and contains more alkoxyl groupsthan the same lignin contains in its natural state.

In attempting to accomplish resinification of alkoxyl lignin halidethrough polymerizationcondensation type reactions conducted according topreferred prior art practices, I found that even by very closelycontrolling time and temperature conditions, it is impossible to obtainconsistently a resinous product having the desired properties andcharacteristics. However, I have discovered an entirely unique processby which said resinous product can be prepared, and using that process,I have prepared what I believe is the'flrst light-colored, transparent,polymerized, alkoxyl lignin halide resin known to the art. In addition,I found that with the process of my invention, it is possible to producethe desired product without the exercise of very close control overconditions attending the reaction, it being essential only that theproper raw material be used, that the temperature of the reaction bemaintained within the range between of about 45 C. and about C. and thatadequate time be allowed for the reaction.

Briefly stated, the present invention comprises the step of maintaininga solution of alkoxyl lignin halide in an organic solvent substantiallynon-reactive therewith under time and temperature conditions rangingbetween about 45 C. for longer than about 72 hours and about 150 C. forlonger than about 4 hours, while said solution is in contact with apolymerization catalyst and is maintained under a. halogen atmosphere.

Although I have found it possible to obtain consistently satisfactoryresults by operating the process for only about 4 hours, I prefer tocarry it out over a period of at least 10 hours and preferably ingeneral practice for between about and about 20 hours.

The process of my invention may be carried out in vacuo, at atmosphericpressure, or elevated pressures, with the solvent under reflux in orderto control the rate of reaction or to maintain the solvent substanceemployed in the liquid state.

The invention will be better understood by those skilled in the art fromthe following illustrative, but not limiting examples.

Example I 10 grams of methoxyl lignin chloride obtained by theabove-described process from redwood was dissolved in 100 cc. ofmethanol. 0.1 gram of benzoyl peroxide was added and the solution wasrefluxed for twenty-four hours at atmospheric pressure and at 65-70" C.Chlorine gas was bubbled through the solution throughout the refluxperiod. Approximately two-thirds of the methoxyl lignin chloride chargedseparated ,from the methanol as an insoluble transparent yellow resin.The balance Of the polymer yield was obtained by pouring the supernatentmethanol layer into water, whereupon a resinous material separated.

Example II 100 grams of methoxyl lignin chloride obtained by theabove-described process from jack pine was dissolved in 500 cc. ofmethanol. 1.0 gram of benzoyl peroxide was added and the mixture wasrefluxed for forty-eight hours at 65-70 C. A practically quantitativeyield of methanol insoluble polymer was obtained. No appreciable amountof polymer or methoxyl lignin chloride was found in the supernatentmethanol layer.

Example III 25 grams of methoxyl lignin chloride obtained by theabove-described process from redwood was dissolved in 250 cc. ofmethanol. 0.25 gram of benzoyl peroxide was added and the mixture wasrefluxed for seventy-two hours at 65'70 C. All of the polymer wasobtained as a methanol insoluble product.

The foregoing examples set forth certain illustrative raw materials andreaction conditions, but alkoxyl lignin halides from other tree andplant fibers may be used with similar results and under similarconditions. Likewise, other organic solvents or mixtures thereof for thealkoxyl lignin halides may also be used without changing the type ofreaction so long as they are not substantially reactive with the saidhalides during this processing period. Alcohols in addition to methanolwhich have satisfactory solvent properties include ethanol, n-propanol,iso-propanol and nbutanol. Aldehydes and ketones which are suitableinclude formaldehyde, actaldehyde, propionaldehyde, benzaldehyde,acetone, hydroxyacetone, methyl ethyl ketone, acetoin, propionone andbutyrone. Ethers and esters having satisfactory solvent propertiesinclude methyl ether, ethyl ether, n-propyl ether, iso-propyl ether,n-butyl ether, methyl formate, methyl acetate, ethyl formate, ethylacetate, propyl formate, and methyl propionate. Also fluorine, bromineor iodine may be used instead of chlorine to produce satisfactoryresults, and they may be used separately or in any admixture with eachother and chlorine.

Organic carboxylic acids and 'anhydrides thereof, being reactive withalkoxyl lignin halides as described in my copending application SerialNumber 447,443, filed June 17, 1942, and now abandoned and acontinuation-in-part of said application identified as Serial Number495,625 filed June 21, 1943, now abandoned, are unsuited as solvents forsaid halides in the present process.

Although benzoyl peroxide is the only catalyst referred to specificallyin the examples, other well known polymerization catalysts may be used9.1- ternatively or conjointly to accomplish similar results. Forinstance, aluminum chloride, aluminum fluoride, boron fluoride, titaniumtetrachloride, ferric chloride, oxygen,,ozone, organic peroxides,organic ozonides, persulfates, percarbonates, perborates, metallicsodium (in difierent solvents) and mineral acids are suitable ascatalysts for the reaction of this process. As those skilled in the artwill readily understand, the amount by weight of a given catalyticsubstance necessary to obtain the desired catalytic result will likelynot be the same as the amount required of another such substance to gainthe same result. But this does not imply that much experimentation isrequired to determine the required quantity of a catalyst for use inthis process. The polymerization here resembles generally, so far ascatalytic action is concerned, other well known polymerizations and,therefore, one practicing the present inventioncan be guided byknowledge of such other polymerizations in the selection of and the useof the catalytic substance.

Reaction conditions may be varied with regard to time of reflux,temperature and pressure, so as to control the rate and degree ofpolymerization. Extending the time of reflux results in more completepolymerization of the lignin halide and has a bearing upon stability, aswill be seen by comparison of Example II with Example I. Generally, anincrease in temperature and/or pressure reduces the time required forcomplete polymerization by increasing the rate.

The alkoxyl lignin halide polymers thus obtained are useful for manypurposes, as, for example, in plastics, and as base materials for var-.nishes and coatings for paper, and other mateshould have a vapor-refluxduct at its top, the' vapor duct leading to an overhead condenser fromwhich the condensate constantly returns to the vessel. For reducedpressures a usual type of vacuum pump may be connected to the top of thecondensing tube. Such apparatus is standarddn the resin art.

In this specification and in the appended claims percentage andproportions are expressed on the weight basis.

This application is a continuation-in-part of application Serial No.495,626, filed July 21, 1943, now abandoned.

Having thus described the present invention so that others skilled inthe art may be able to understand and practice the same, I state thatwhat I desire to secure by Letters Patent is de- 2. The method ofpreparing light-colored,

lignin chloride at a temperature 01' less than about,

150 C. for between about 10 hours and about 72 hours, while saidsolution is in contact with benzoyl peroxide and is under a chlorineatmosphere, and then boiling oi! the methanol at a temperature belowabout 150 C.

3. The method or preparing light-colored, transparent to translucent,thermoplastic methoxyl lignin chloride resins which comprises the stepsof refluxing a methanol solution of methoxyl lignin chloride at atemperature less than about 150 C. for between about 10 hours and about72 hours, while said solution is in contact with benzoyl peroxide and isunder a chlorine atmosphere, separating and recovering the resultinginsoluble resinous material, mixing the remaining solution with morethan its volume of water and separat- Means ing and recovering theresinous material which separates.

RAPHAEL KATZEN.

REFERENCES CITED The following references are of record in the file ofthis patent: J UNITED STATES PATENTS 1 Number Name Date 2,212,866Sherrard Aug. 27, 1940 OTHER REFERENCES Friedrich: Biochem, Zeit., vol.239,, pp. 461-472 (1931).

Muller: Der Papieri'abrikant, Technisch-Wissenschaftiicher Teil, vol. 37pp. 237-240 (1939).

